"They're protected by the piece of his soul inside them," Harry said. "And you have to use something special, something really potent, to destroy it. We have Godric's sword, it's worked on them all so far."
He sighed and ran a hand nervously through his hair. He wasn't even sure if he should be telling Neville all of this - but Neville had insisted on knowing, and there was really no one Harry trusted more, outside of the people he'd already trusted. Which didn't make it easier, because the information put Neville in danger.
Then again, he didn't want Neville going crazy from feeling like he was doing nothing useful, because he knew how that felt. That kind of situation could be even more dangerous to him than having knowledge, having purpose.
"And, well, it's a snake - the rest weren't alive. And it's kept close to You-Know-Who. That makes it the hardest of them all." He looked at Neville. "I'm going to try to destroy it - I have to get close to him to kill him, anyway. But if I can't, make sure that the snake dies. Or V- You-Know-Who will come back."
It was still ridiculously hard to remember, sometimes, not to say Voldemort's real name aloud, even though he'd learned the lesson the hard way that there was a trace on it. He really didn't want to bring any Snatchers down on their heads, not right now.